The present disclosure generally relates to the field of stimulating tissue growth and healing, and more particularly to an apparatus and method for monitoring and controlling the transmissibility of mechanical vibration energy during dynamic motion therapy. More specifically, the present disclosure relates to therapeutically treating damaged tissues, bone fractures, osteopenia, osteoporosis, or other tissue conditions, as well as postural instability, using dynamic motion therapy and mechanical impedance methods to predict and maximize the transmissibility of mechanical vibration energy through a patient's body.
When damaged, tissues in a human body such as connective tissues, ligaments, bones, etc. all require time to heal. Some tissues, such as a bone fracture in a human body, require relatively longer periods of time to heal. Typically, a fractured bone must be set and then the bone can be stabilized within a cast, splint or similar type of device. This type of treatment allows the natural healing process to begin. However, the healing process for a bone fracture in the human body may take several weeks and may vary depending upon the location of the bone fracture, the age of the patient, the overall general health of the patient, and other factors that are patient-dependent. Depending upon the location of the fracture, the area of the bone fracture or even the patient may have to be immobilized to encourage complete healing of the bone fracture. Immobilization of the patient and/or bone fracture may decrease the number of physical activities the patient is able to perform, which may have other adverse health consequences. Osteopenia, which is a loss of bone mass, can arise from a decrease in muscle activity, which may occur as the result of a bone fracture, bed rest, fracture immobilization, joint reconstruction, arthritis, and the like. However, this effect can be slowed, stopped, and even reversed by reproducing some of the effects of muscle use on the bone. This typically involves some application or simulation of the effects of mechanical stress on the bone.
Promoting bone growth is also important in treating bone fractures, and in the successful implantation of medical prostheses, such as those commonly known as “artificial” hips, knees, vertebral discs, and the like, where it is desired to promote bony ingrowth into the surface of the prosthesis to stabilize and secure it. Numerous different techniques have been developed to reduce the loss of bone mass. For example, it has been proposed to treat bone fractures by application of electrical voltage or current signals (e.g., U.S. Pat. Nos. 4,105,017; 4,266,532; 4,266,533, or 4,315,503). It has also been proposed to apply magnetic fields to stimulate healing of bone fractures (e.g., U.S. Pat. No. 3,890,953). Application of ultrasound to promoting tissue growth has also been disclosed (e.g., U.S. Pat. No. 4,530,360).
While many suggested techniques for applying or simulating mechanical loads on bone to promote growth involve the use of low frequency, high magnitude loads to the bone, this has been found to be unnecessary, and possibly also detrimental to bone maintenance. For instance, high impact loading, which is sometimes suggested to achieve a desired high peak strain, can result in fracture, defeating the purpose of the treatment.
It is also known in the art that low level, high frequency stress can be applied to bone, and that this will result in advantageous promotion of bone growth. One technique for achieving this type of stress is disclosed, e.g., in U.S. Pat. Nos. 5,103,806; 5,191,880; 5,273,028; 5,376,065; 5,997,490; and 6,234,975, the entire contents of each of which are incorporated herein by reference. In this technique (referred to as dynamic motion therapy), the patient is supported by an oscillating platform apparatus that can be actuated to oscillate vertically, so that resonant vibrations caused by the oscillation of the platform, together with acceleration brought about by the body weight of the patient, provides stress levels in a frequency range sufficient to prevent or reduce bone loss and enhance new bone formation. The peak-to-peak vertical displacement of the platform oscillation may be as little as 2 μm.
However, these systems and associated methods often depend on an arrangement whereby the operator or user must measure the weight of the patient and make adjustments to the frequency of oscillation to achieve the desired therapeutic effect. U.S. Pat. No. 6,843,776 discloses an oscillating platform apparatus that automatically measures the weight of the patient and adjusts characteristics of the oscillation force as a function of the measured weight, to therapeutically treat damaged tissues, bone fractures, osteopenia, osteoporosis, or other tissue conditions.
It is an aspect of the present disclosure to provide an alternative oscillating platform apparatus and associated circuitry for determining the weight of the patient using two angular measurements and making adjustments to the frequency of oscillation and/or the amplitude of the frequency of oscillation in accordance with the calculated weight of the patient to achieve the desired therapeutic effect.
It is also known in the art that the application of low level, high frequency stress is effective in treating postural instability. A method of using resonant vibrations caused by the oscillation of a vibration table or unstable vibrating platform for treating postural instability is described in U.S. Pat. No. 6,607,497 B2; the entire contents of which are incorporated herein by reference. The method includes the steps of (a) providing a non-invasive dynamic therapy device having a vibration table with a non-rigidly supported platform; (b) permitting the patient to rest on the non-rigidly supported platform for a predetermined period of time; and (c) repeating the steps (a) and (b) over a predetermined treatment duration. Step (b) includes the steps of (b1) measuring a vibrational response of the patient's musculoskeletal system using a vibration measurement device; (b2) performing a frequency decomposition of the vibrational response to quantify the vibrational response into specific vibrational spectra; and (b3) analyzing the vibrational spectra to evaluate at least postural stability.
The method described in U.S. Pat. No. 6,607,497 B2 entails the patient standing on the vibration table or the unstable vibrating platform. The patient is then exposed to a vibrational stimulus by the unstable vibrating platform. The unstable vibrating platform causes a vibrational perturbation of the patient's neuro-sensory control system. The vibrational perturbation causes signals to be generated within at least one of the patient's muscles to create a measurable response from the musculoskeletal system. These steps are repeated over a predetermined treatment duration for approximately ten minutes a day in an effort to improve the postural stability of the patient.
The patient undergoing vibrational treatment for treating postural instability and/or the promotion of bone growth, as described above, may experience a level of discomfort due to whole-body vibration acceleration. The level of discomfort caused by vibration acceleration depends on the vibration frequency, the vibration direction, the point of contact with the body, and the duration of the vibration exposure. It is desirable to monitor at least one mechanical response of the body during vibrational treatment in an effort to control the at least one mechanical response to influence comfort level, as well as to determine patient- and treatment-related characteristics. Two mechanical responses of the body that are often used to describe the manner in which vibration causes the body to move are transmissibility and mechanical impedance.
Transmissibility describes the fractional relationship of the vibration which is transmitted from, say, the vibration table or oscillating platform apparatus to the head of the patient. The transmissibility of the body is highly dependent on vibration frequency, vibration axis and body posture. Vertical vibration on The non-invasive dynamic therapy device causes vibration in several axes at the head; for vertical head motion, the transmissibility tends to be greatest in the approximate range of 3 to 10 Hz.
The mechanical impedance of the body shows the force that is required to make the body move at each frequency. Although the impedance depends on body weight, the vertical impedance of the human body usually shows a resonance at about 5 Hz. The mechanical impedance of the body, including this resonance, has a large effect on the manner in which vibration is transmitted through seats.
Accordingly, it is an aspect of the present disclosure to use mechanical impedance methods to predict and make efforts to maximize the transmissibility of the mechanical vibration energy through a patient standing on an oscillating platform apparatus and performing exercises and/or being treated using dynamic motion therapy for bone fractures, osteopenia, osteoporosis, or other tissue conditions, postural instability, or other conditions, such as cystic fibrosis, Crohn's disease and kidney and gall bladder stones, as described in U.S. patent application Ser. No. 11/207,335 filed on Aug. 18, 2005; the entire contents of the provisional patent application are incorporated herein by reference.
It is also an aspect of the present disclosure to use mechanical impedance methods in designing a seat or other support structure to be supported by the oscillating platform apparatus which will maximize the transmissibility of the mechanical vibration energy through the oscillating platform apparatus-seat/support structure-patient interface.